Initiating Photocontrolled Atom Transfer Radical Polymerization from a Redox-Activated Functional Group

Initiating controlled radical polymerizations directly from common functional groups is desirable for synthesizing advanced polymer architectures, such as surface grafts and polymer conjugates. Previously, photocontrolled atom transfer radical polymerization (ATRP) has been performed with alkyl halide initiators, limiting its utility in these advanced polymer applications. In this study, we demonstrate the initiation of photo-ATRP directly from the α-carbon of primary amines. We employ an iridium photocatalyst to trigger radical deamination of redox-activated primary amines, initiating controlled radical polymerization in the presence of an exogenous bromide source under visible light irradiation. The resulting polymers have narrow molar mass distributions (Đ ∼ 1.2-1.3), good agreement between theoretical and experimental molar masses, exceptionally high α-chain-end fidelities (>99%), and active bromide ω-chain-ends. This study lays the groundwork for utilizing non-alkyl halide initiators to initiate well-controlled ATRP polymerizations, opening the door for the use of redox-activated functional groups as ATRP initiators for creating advanced polymer architectures.